It is well known in the art to employ reaction jets that vary the pitch, yaw, spin rate and other dynamic characteristics of a missile or space vehicle in flight. A typical reaction jet comprises a jet nozzle and a housing defining a main stage plenum. An annular passage supplies pressurized fluid to the main stage plenum to be discharged through the jet nozzle, thereby creating reaction jet thrust. Disposed within the reaction jet housing is a valve member, often comprising a poppet valve. The poppet valve regulates the flow of pressurized fluid from the annular passage through the jet nozzle by moving alternately between a fully opened position and a closed position.
In the fully open position, the poppet valve is retracted from a position abutting a valve seat formed between the annular passage and the nozzle. In the closed position, the poppet valve is position in abutment with the valve seat thereby sealing the annular passage from the plenum. The poppet valve is urged between the open and closed positions by the pressure balance between the fluid pressure in the plenum and the fluid pressure in a main stage actuation chamber. When the pressure in the main stage actuation chamber is greater than the pressure in the plenum, the poppet valve is urged towards the closed position. Conversely, when the pressure in the main stage actuation chamber drops such that the pressure in the plenum is greater than the pressure in the main stage actuation chamber, the poppet valve is urged toward the fully open position. The actuation chamber normally is axially aligned with the poppet valve and disposed on the opposite side of the poppet valve from the plenum. Accordingly, the actuation chamber is of approximately the same diameter as the poppet valve such that the working volume of the actuation chamber volume is approximately equal to the swept volume of the poppet valve.
Typically, the main stage actuation chamber is pressurized and vented by a pilot valve. Control of pilot valve pressurization and venting conventionally is achieved by a solenoid-actuated flapper valve, which opens and closes to admit or vent high pressure gas to and from the main stage actuation chamber.
Because missiles and space vehicles typically move at high rates of speed, it is critical to the control of such craft that the reaction jets have a high rate of response between their respective on and off positions. Accordingly, it is desirable to minimize the time and work necessary to move the poppet valve between the open and closed positions. At the same time, in order to preserve desired mass flow rate through the nozzle, the plenum and poppet valve diameters must be maintained. These objectives may be achieved by minimizing the actuation chamber volume and/or minimizing aerodynamic resistance of the poppet valve member movement within the valve body.
Accordingly, a need exists for a reaction jet valve that provides maximum flow rate through the nozzle with minimal time and work needed to control the flow through the nozzle.